MADRID — Novak Djokovic has withdrawn from the Madrid Open because of illness and allergies.

The Serb is ranked No. 2 and retired from the Serbia Open quarterfinals against Filip Krajinovic on Friday because of a fever.

Organizers said Saturday that because of Djokovic's withdrawal Andy Murray moves up to become the third seeded player in the clay-court tournament. Last year's winner, Roger Federer, is seeded No. 1, followed by 2009 finalist Rafael Nadal.

Qualifying matches began Friday. The tournament ends May 16.